9 unit of measurement velocity, 2 data exchange during normal operation – ifm electronic RN3001 User Manual
Page 19
UK
Encoder with Profibus interface
19
10.1.9 Unit of measurement velocity
The unit for the velocity value to be provided (class ifm 2�2) can be set via this
parameter�
Unit
Bit 4
Bit 5
Steps / second
0
0
Steps / 100ms
1
0
Steps/10ms
0
1
Revolutions / minute
1
1
10.2 Data exchange during normal operation
The process actual value is in general transferred as a 32-bit word (double word)
with the manufacturer-specific encoder classes ifm 2�1 and ifm 2�2� In addition to
the 25 bits that are provided for the position value 7 other bits are used as status
bits� In the (peripheral) output double word the master sends the preset value and
in addition the control bits to the encoder�
For encoders of this type more than 25-bit absolute position data may be available�
The position values < 25 bits are not supported in the ifm classes; the more
significant bits are overwritten by status bits�
If the ifm classes are to be used with encoders whose physical resolution exceeds
25 bits, the user must ensure that the physical position value is scaled to a (max�)
output value < 33554432 (via parameter setting)� If absolute values > 25 bits are
required, Class 2 has to be selected�
An additional (peripheral) input word of the current velocity value is transferred
with device class ifm 2�2�
Identifica-
tion
F1 hex
D0 hex
Encoder →
master
Status + position actual value
Velocity
Status + 2
24
2
23
- 2
16
2
15
- 2
8
2
7
- 2
0
2
15
- 2
8
2
7
- 2
0
Master →
encoder
Preset value + control bits
Control + 2
24
2
23
- 2
16
2
15
- 2
8
2
7
- 2
0